Interesting article. Despite what some delusional posters may say, the Democrats accepted Trump's victory as evidenced by Hillary's concession speech. If either candidate wins decisively then there really is no issue. If Biden wins the popular vote by a slim margin but loses the electoral college I don't expect much in the way of unrest. The problem comes in is if Trump wins the electoral college and loses the popular vote by let us say more than 5,000,000 votes. Let us further presume that Biden wins greater than 50% of the vote as well. We are not talking a slim margin of the vote for Biden but a substantial margin of the popular vote. It would mean that Republicans have not won the popular vote in the last three out of four times they won the presidency. I would then expect some unrest, but that Trump would be eventually inaugurated as president. There will be a growing chorus to abolish the electoral college which I agree with Bryon may be a compromise.
My own prediction is that Biden wins decisively enough where there is no doubt who won.